Process for the vulcanization of epdm elastomers

ABSTRACT

Oxazolidine and thiazolidinecarbodithioates, and pyridine adducts thereof, are accelerators for the vulcanization of EPDM elastomers, wherein they exhibit non-blooming characteristics.

This application is a division of copending application Ser. No.438,819, filed Feb. 1, 1974, now U.S. Pat. No. 3,943,143, issued Mar. 9,1976 which is a continuation-in-part of application Ser. No. 356,034,filed Apr. 30, 1973, now abandoned, which is a continuation-in-part ofapplication Ser. No. 259,900, filed June 5, 1972, now abandoned, whichin turn is a continuation-in-part of application Ser. No. 116,250, filedFeb. 17, 1971, now U.S. Pat. No. 3,674,701.

This invention relates to compounds which are active accelerators forthe vulcanization of elastomers, and more particularly to zincoxazolidinecarbodithioates and zinc thiazolidinecarbodithioates andtheir pyridine adducts which are especially useful in retarding surfacebloom in vulcanized elastomers, especially in elastomeric terpolymers ofethylene, propylene and a dienemonomer (EPDM elastomer).

In the process of vulcanization of elastomers using an accelerator inconjunction with sulfur or other vulcanization agent, there has been aneed for a non-blooming type of accelerator that has adequateaccelerator activity. Zinc dithiocarbamates, such as zinc dimethyl-anddiethyldithiocarbamate, have high activity as accelerators but they givean undesirable surface bloom on elastomer vulcanizates. Surface bloom isa disadvantageous phenomenon characterized by the appearance of acoating of solids or oil upon the surface of a vulcanizate as a resultof the migration to the surface of one or more of the components of thevulcanized elastomer. This may occur quickly, as for example, in a fewdays or a week. Blooming is also particularly a problem in the case ofEPDM elastomers, which are terpolymers of ethylene, propylene anddiene-monomer, for example, 11-ethyl-1, 11-tridecadiene,1,5-cyclooctadiene, 1,5-hexadiene, 5-ethylidene-2-norbornene,5-methylene-2-norbornene, dicyclopentadiene, 2,5-norbornadiene and thelike. Moreover, the curing of the EPDM elastomer requires a highactivity accelerator because of the low level of unsaturation in thepolymer.

U.S. Pat. No. 3,674,701 discloses a non-blooming accelerator compositioncomprised of a mixture of a certain thiourea compound with the zinc saltof the reaction product of essentially equimolar amounts ofethanolamine, formaldehyde and carbon disulfide. We have now managed toisolate, through solvent extractions and crystallizations, a particularnovel compound from said complex reaction product mixture, which, byitself, is a non-blooming accelerator, that is, a thiourea or otheradjunct is not required to be mixed therewith for good results in EPDMvulcanization. This invention embodies this novel compound and the classof related oxazolidinecarbodithioates and thiazolidinecarbodithioateswhich have surprising non-blooming accelerator activity.

The compound of this invention is represented by the structure ##SPC1##

where X is sulfur or oxygen, R, R¹ R², and R³ are independently selectedfrom the group consisting of hydrogen, lower alkyl (e.g., having from 1to 8 carbon atoms, and preferably methyl), CCl₃, phenyl, and substitutedphenyl wherein there are one or more substituents selected from thegroup consisting of NR⁴ R⁵, OH, OR⁴ and Cl where R⁴ and R⁵ areindependently selected from the group consisting of hydrogen and loweralkyl (C₁ -C₈); C₅ H₅ N represents a pyridine molecule and n is aninteger of zero to 5, preferably 0 to 3, the higher values of nresulting from acidic characteristics of the substituents; M is selectedfrom the group consisting of sodium, potassium, zinc, cadmium, copper,iron, tri-(lower) alkyl substituted ammonium, and phenyl-di-(lower)alkyl substituted ammonium; and y is an integer of 1 to 3, depending onthe valency of M (ion). The preferred M ions are zinc and triethylammonium.

A convenient method of preparing the compounds of this invention is tofirst prepare an oxazolidine or thiazolidine (or substituted derivativethereof), represented by the formula ##SPC2##

(where X is oxygen or sulfur) involving the reaction of an amino alcoholor an amino mercaptan with an aldehyde or ketone. When formaldehyde isused, the resulting intermediary triazine is pyrolized at about 100° to200° C., in accordance with the procedure suggested by A. Paquin, Ber.82, 316 (1949). A typical preparation of the unsubstituted oxazolidineis as follows, employing the reaction scheme as shown:

EXAMPLE 1 Preparation of Oxazolidine from 1, 3,6-tris(2-hydroxyethyl)hexahydro-1, 3, 6-triazine ##SPC3##

With stirring, 486 g. (6.0 moles) of 37% formaldehyde solution was addeddropwise to 366 g. (6.0 moles) of ethanolamine at 40° - 45° C. After anadditional hour at 40° - 45° C the water was removed in a rotary vacuumevaporator at 50° - 55° C to leave a residue of 447 g. amber colored oilas the 1, 3, 5-tris(2-hydroxyethyl)hexahydro-1, 3, 5-triazine containing18.98% N (calc. 19.17% N).

A 24.1 g. portion of the above triazine was distilled in a Pyrexglass-still having distillate receiver cooled by a Dry Ice-acetone bath(-75° C). Vapor temperature was 52° - 69° C at 1.2 mm. pressure. Thestill-pot temperature was 118° - 139° C. Temperature of the oil bathsurrounding the stillpot was 153° - 172° C. The distillate was 22.2 g.of colorless oxazolidine (very visous at -75° C).

The oxazolidinecarbodithioates and thiazolidinecarbodithioates of thisinvention are obtained by reacting an oxazolidine (or thiazolidine) withcarbon disulfide and the desired metal salt, or metal oxide, or amine,at about 0° to 100° C. in an appropriate solvent such as pyridine,triethylamine, tributylamine, methanol, isopropanol, ethanol andbutanol, desirably containing a minor proportion of a basic amine suchas triethylamine, tributylamine, pyridine, dimethylaniline anddiethylaniline. The preferred solvent system, however is pyridine, whichacts not only as the reaction medium but provides the desired basicity.The products of the reaction will then generally be recovered as apyridine adduct thereof, containing as many as five molecules ofpyridine. The pyridine can usually be removed from the zinc salt byheating the adduct up to about 50° to 150° C under reduced pressure, butthis is not necessary since the presence of the pyridine in the saltdoes not in anyway impede the good performance of the compounds asnon-blooming vulcanization accelerators. The following examplesillustrate the preparation of representative compounds of thisinvention.

EXAMPLE 2 Preparation of Zinc Bis(3-oxazolidinecarbodithioate) ##SPC4##

With stirring and cooling to maintain 15° - 25° C, 111.1 g. (1.52 mole)of freshly distilled, cold oxazolidine [prepared from 1, 3,5-tris(2-hydroxyethyl)hexahydro-1, 3, 5-triazine, as described by A.Paquin, Chem. Ber. 82, 316 (1949)] was added to a mixture of 600 g.pyridine, 116 g. (1.52 moles) carbon disulfide and 139.5 g. (0.76 mole)anhydrous zinc acetate. After standing overnight at room temperature,the precipitated product was filtered, water-washed and air-dried togive 193.5 g. of a mono pyridine adduct, m. p. 195° - 200° C (decomp.);dilution of the filtrate with water gave an additional 34.4 g. (totalconversion 68.3%).

Vacuum-drying of the pyridine adduct at 80° - 85° C removed the pyridine(weight loss indicates a 1:1 mole ratio of pyridine to zinc salt to givethe desired zinc bis(3-oxazolidinecarbodithioate), a white, crystallineproduct melting at 223° - 225° C (decomp.). It had the followinganalysis:

Found: C, 26.75; H, 3.46; N, 7.63; Zn, 17.9%; Calcd for C₈ H₁₂ N₂ O₂ S₄Zn: C, 26.56; H, 3.32; N, 7.75; Zn, 18.10%.

EXAMPLE 3 Preparation of ZincBis(2-trichloromethyl-3-oxazolidinecarbodithioate) ##SPC5##

Ninety-five and two-tenths g. of 2-trichloromethyloxazolidine(preparation described by W. Ruske and I. Hartmann, J. Prakt, Chem. 18,146 (1962)) was dissolved in a mixture of 300 ml isopropanol, and 50.5g. (0.50 mole) of carbon disulfide was added dropwise followed by 43.9g. (0.25 mole) of anhydrous zinc acetate. The reaction mixture washeated for two hours at 45° - 50° C, cooled to room temperature, anddiluted with 1 liter water; the precipitated product was filtered,washed thoroughly with water and dried in vacuo to give 86.3 g. of thecrude product, melting at 193° - 195° C (decomp.). Hot benzeneextractions of the crude product gave 38 g. of the desiredcarbodithioate sintering at 208° C, and melting 213° - 216° C (decomp.).It had the following analysis:

Found C, 20.19; H, 2.08; N, 4.67; S, 20.96%; Calcd for C₁₀ H₁₀ Cl₆ N₂ O₂S₄ Zn: C, 20.12; H, 1.68; N, 4.69; S, 21.46%.

EXAMPLE 4 Preparation of Zinc Bis(2-trichloromethyl-3-oxazolidinecarbodithioate) Pyridine Adduct ##SPC6##

Thirty and four-tenths grams (0.160 mole) of2-trichloromethyloxazolidine (preparation described by W. Ruske and I.Hartmann, J. Prakt. Chem. 18, 146 (1962)) was dissolved in 480 g. ofpyridine. With rapid stirring at room temperature, 14.4 g. (0.184 mole)of carbon disulfide was added dropwise followed by 15.2 g. (0.083 mole)of anhydrous zinc acetate. The reaction mixture was heated 3 hours at45° - 50° C, cooled to room temperature, and then diluted with 1 literwater; the precipitated product was filtered and dried in vacuo at roomtemperature to obtain 33.4 g. of the desired pyridine adduct melting at205° - 207° C (decomp.). A small analytical sample, recrystallized inmethanol, sintered at 209° C and melted with decomposition at 212° -214°C. It had the following analysis:

Found: C, 26.70; H, 2.74; N, 6.30; S, 19.60; Cl, 31.37; Zn, 9.55%; Calcdfor C₁₀ H₁₀ Cl₆ N₂ O₂ S₄ Zn . C₅ H₅ N: C, 26.65; H, 2.22; N, 6.23; S,18.95; Cl, 31.54; Zn, 9.68%.

EXAMPLE 5 Preparation of Zinc Bis(2,2-dimethyloxazolidine-3-carbodithioate) ##SPC7##

While cooling and stirring, 20 g. (0.20 mole) of 2,2-dimethyloxazolidine(preparation described by E. Bergmann et. al., J. Am. Chem. Soc. 75, 358(1953)) was added to a solution of 15.2 g. (0.20 mole) carbon disulfidein 150 g. pyridine. To the stirring solution was added 18.3 g. (0.10mole) of anhydrous zinc acetate at 25° - 30° C. After standing overnightat room temperature, filtration gave 15.2 g. of the crude product;vacuum-concentration of the filtrate and ethanol-dilution of the residuegave an additional 10.4 g. After combining and vacuum-drying of thecrude product at 100° C there was obtained 17.8 g. of the desiredcarbodithioate melting at 188° - 190° C (decomp.). A small sample,dissolved in hot chloroform and precipitated by hexane (m. 192° - 3° Cdecomp.) had the following analysis:

Found: C, 34.22; H, 4.47; N, 6.84; Zn, 15.20%; Calcd for C₁₂ H₂₀ N₂ O₂S₄ Zn: C, 34.50; H, 4.79; N, 6.71; Zn, 15.67%

EXAMPLE 6 Preparation of ZincBis[2-(3-ethoxy-4-hydroxyphenyl)oxazolidine-3-carbodithioate]Tripyridine Adduct ##SPC8##

A mixture of 80 ml isopropanol, 15.7 g. (0.094 mole)3-ethoxy-4-hydroxybenzaldehyde and 6.0 g. (0.098 mole) ethanolamine washeated on the steam bath for 1 hour. Filtration at room temperature gave19.3 g. of crystals melting at 157° - 160° C. On the basis of its IRspectrum [1650 cm⁻ ¹ for C=N, L. W. Daasch, J. Am. Chem. Soc. 73, 4523,(1951)] the product appeared to be primarily the Schiff Baseβ-(3-ethoxy-4-hydroxybenzylideneamino)-ethanol which can be intautomeric equilibrium with the cyclic2-(3-ethoxy-4-hydroxyphenyl)oxazolidine.

The mixture of the above crystals with 40 g. of pyridine, 7.6 g. (0.10mole) of carbon disulfide and 9.2 g. (0.050 mole) of anhydrous zincacetate was heated for 1.5 hours at 50° - 55° C and then left standingovernight at room temperature. Filtration and hexane-washing of theprecipitate gave 38.1 g. of the pyridine adduct melting at 106° - 112° Cand having the following analysis:

Found: C, 53.25; H, 4.95; N, 7.74; Zn, 7.46%; Calcd for C₂₄ H₂₈ N₂ O₆ S₄Zn. 3C₅ H₅ N: C, 53.77; H, 4.94; N, 8.04; Zn, 7.51%.

The IR-spectrum of this product did not show any absorption at 1650 cm⁻¹ characteristic of the Schiff Base discussed above. This proved thatthe Schiff Base tautomerized to the corresponding oxazolidine which inturn reacted with CS₂ and Zn(OAc)₂.

EXAMPLE 7 Preparation of ZincBis[2-(p-dimethylaminophenyl)oxazolidine-3-carbodithioate), PyridineAdduct

This product was prepared as described in Example 6 usingp-dimethylaminobenzaldehyde instead of 3-ethoxy-4-hydroxybenzaldehyde.The evaporation residue was washed with water and the remaining solidwas dissolved in dimethylformamide at room temperature. The filteredsolution was diluted with water to obtain the product melting at 91° -93° C (decomp.). Its structure ##SPC9##

was confirmed by IR spectrum and elemental analysis:

Found: C, 51.72; H, 5.82; Zn, 9.13%; Calcd for C₂₄ H₃₀ N₄ O₂ S₄ Zn.C₅ H₅N: C, 51,30; H, 5.16; Zn, 9.64%.

EXAMPLE 8 Preparation of Zinc Bis(thiazolidine-3-carbodithioate)##SPC10##

While cooling and stirring 250 g. of pyridine, 175 g. (1.40 moles) ofthiazolidine hydrochloride [preparation described by S. Ratner and H.Clarke, J. Am. Chem. Soc. 59, 200 (1937)] was added. After it haddissolved, 106.4 g. (1.40 mole) of carbon disulfide was added dropwise,followed by 128.5 g. (0.70 mole) of anhydrous zinc acetate. Theresulting reaction mixture was stirred at 40° - 50° C for 2 hours. Theprecipitate was filtered at 5° - 10° C. The crude solid was water-washedand finally freed of pyridine by vacuum-drying at 120° C to give 147.8g. of the desired product. It gradually decomposed starting at ca. 200°C without a definite final decomposition point. A small sample washedwith hot benzene had the following analysis:

Found: C, 24.46; H, 2.95; N, 7.31; Zn, 16.58%; Calcd for C₈ H₁₂ N₂ S₆Zn: C, 24.40; H, 3.05; N. 7.12; Zn, 16.62%.

EXAMPLE 9 Preparation of ZincBis[(2-trichloromethyl)thiazolidine-3-carbodithioate] Dipyridine Adduct##SPC11##

To 158.2 g. (2.0 moles) of pyridine was added 66.0 g. (0.32 mole) of2-trichloromethylthiazolidine [preparation described by B. Sweetman etal, J. Med. Chem. 12, 888 (1969)] and to the resulting stirred solutionat 20° C was added 24.4 g. (0.32 mole) of carbon disulfide over a10-minute period. The solution was warmed to 25° C, at which temperature29.4 g. (0.16 mole) of zinc acetate was added portionwise over 0.5-hr.period. The temperature was maintained at 25° C with an ice bath duringthe addition. The resulting clear amber solution was stirred at ambienttemperature for an additional 17 hours. The precipitate, having formedduring the additional stirring time, was filtered and washed with 4 ×500 ml of water. After air-drying, 100 g. (79% conversion) of off-whiteproduct was obtained. Its melting point was 181°-3° C with some gasevolution. It had the following analysis.

Found: C, 30.57, H, 3.01; Cl, 27.36; Zn, 8.1%; Calcd for C₁₀ H₁₀ Cl₆ N₄S₆ Zn.2C₅ H₅ N: C, 30.52, H, 2.56; Cl, 27.07; Zn, 8.3%.

EXAMPLE 10 Preparation of ZincBis(2,2-dimethylthiazolidine-3-carbodithioate) ##SPC12##

While cooling and stirring at 10° C, 76.8 g. (0.50 mole)2,2-dimethylthiazolidine hydrochloride [preparation described by B.Sweetman et al, J. Med. Chem. 12, 888 (1969)] was added to a mixture of30 ml isopropanol and 101 g. (1.00 mole) triethylamine. Likewise, 38.0g. (0.50 mole) of carbon disulfide was gradually added, followed by 45.8g. (0.25 mole) of anhydrous zinc acetate. After standing overnight atroom temperature, the precipitate was filtered, twice water-washed with1 liter portions of water and air-dried to give 80.5 g. of the yellowproduct melting at 148° - 153° C (decomp.) and having the followinganalysis:

Found: C, 31.51; H, 4.70%; Calcd for C₁₂ H₂₀ N₂ S₆ Zn: C, 32.04; H,4.45%.

EXAMPLE 11 Preparation of ZincBis[spiro(cyclohexane-1,2'-oxazolidine)-3-carbodithioate] ##SPC13##

Thirty-eight grams (0.50 mole) of carbon disulfide was added withstirring at 10° - 20° C to a mixture of 500 g. isopropanol and 50.5 g.(0.50 mole) triethylamine. To this solution was added 70.5 g. (0.50mole) of spiro(cyclohexane-1,2'-oxazolidine) [preparation described byA. Cope and E. Hancock, J. Am. Chem. Soc. 64, 1503 (1942 )] followed by46.0 g. (0.25 mole) of anhydrous zinc acetate. The reaction mixture wasstirred 4 hours at room temperature. After overnight standing, theprecipitate was filtered to give 97.4 g. of the desired carbodithioatemelting at 198° - 200° C (decomp.). A sample, dissolved in hotdimethylsulfoxide and precipitated by addition of methanol, melted at212° - 213° C and had the following analysis:

Found: C, 42.80; H, 5.41; N, 5.75; Zn, 12.90%; Calcd for C₁₈ H₂₈ N₂ O₂S₄ Zn: C, 43.43; H, 5.63; N, 5.63; Zn, 13.15%.

An alternate and considerably less preferred method of obtaining thezinc salts embodied in this invention is, as mentioned, previously, toisolate the desired compound from the complex reaction of theaminoalkanol (or aminomercaptan), formaldehyde, carbon disulfide andzinc salt precursor by time-consuming solving extraction givinggenerally relatively poor yields. Typical of such a preparation is thefollowing in which the compound of Example 2, zincbis(3-oxazolidinecarbodithioate), is prepared by the alternateprocedure.

EXAMPLE 12

With rapid stirring at 10° - 20° C, 243 g. (3.0 moles) 37% formaldehydesolution was dropwise added to a solution of 183 g. (3.0 moles)ethanolamine in 600 ml of water. The reaction mixture was stirred 1 hourat 50° - 60° C. At 5° - 10° C, 228 g. (3.0 moles) of carbon disulfidewas added dropwise. Stirring was continued for two more hours at 40° -50° C. With rapid stirring at room temperature the reaction mixture wasadded to a solution of 432 g. (1.5 moles) of zinc sulfate heptahydratein 900 ml of water. The precipitate was filtered, water washed andair-dried to give 143.3 g. white crystals. (Accelerator No. 15) meltingat 162° - 175° C (decomp.), a 26.4% conversion.

The product (7 g) was dissolved in 66 cc hot dimethylformamide, cooled,diluted with 20 cc ethanol and filtered. The solid was treated with 300cc hot chloroform, filtered hot, cooled, diluted with 300 cc ethanol andfiltered to obtain 2.2 g (8.3% yield based on ethanolamine) of zincbis(3-oxazolidinecarbodithioate) of Example 2, m.p. 221° (decomp.),containing 26.73%C, 3.44%H, 7.96%N. For calcd. values see Example 2.

EXAMPLE 13 Preparation of ZincBis(2-methyl-2-phenyloxazolidine-3-carbodithioate) Pyridine Adduct

This product was prepared as described for zincbis[2-(3-ethoxy-4-hydroxyphenyl)oxazolidine-3-carbodithioate]tripyridineadduct (Compound No. 6, Example No. 6) using acetophenone instead of3-ethoxy-4-hydroxybenzaldehyde. After the reaction was completed, thereaction mixture was evaporated to dryness and the solid residue wasthoroughly washed with hot isopropanol. The product, m.p. 169° - 173° C(dec.), was identified by its infrared spectrum. It was contaminatedwith some zinc acetate.

EXAMPLE 14 Preparation of Zinc Bis(4-morpholinecarbodithioate) ##SPC14##

To a stirred mixture of 22.0 g. (0.10 mole) of zinc acetate dihydrateand 15.2 g. (0.20 mole) of cabon disulfide in 400 ml of 95% ethanol wasadded slowly 17.4 g. (0.20 mole) of morpholine at 20° - 40° C. Thereaction mixture was filtered to obtain 34.6 g. of the desired solidproduct which did not melt at up to 300° C. A portion of it wasdissolved in chloroform, reprecipitated with hexane and analyzed.

Found: C, 31.40; H, 4.39; N, 7.30; Zn, 16.00; Calcd for C₁₀ H₁₆ N₂ O₂ S₄Zn: C, 30.82; H, 4.11; N, 7.19; Zn, 16.80.

The above product is reported to be a rubber accelerator in C. A. 54,19004 (1960; Russian Patent 127,387 of 3/25/60). No physical propertiesare given in the abstract, but the above analyses confirmed itscomposition.

EXAMPLE 15 Zinc Bis(2-phenyloxazolidine-3-carbodithioate), PyridineAdduct ##SPC15##

The starting material N-(2-hydroxyethyl)-benzalamine, i.e., the tautomerof 2-phenyloxazolidine was prepared from benzaldehyde and ethanolamineby the method of L. Daasch and H. Hanninen, J. Amer. Chem. Soc. 72, 3673(1950).

To the stirred solution of 131 g. (0.88 mole) of N-(2-hydroxyethyl)benzalamine, 68.0 g. (0.88 mole) carbon disulfide and 300 ml. pyridinewas added 81.0 g. (0.44 mole) of anhydrous zinc acetate. After 5 hoursstirring at 25°-45° C. the precipitate was filtered off, washed twicewith 700 ml. 95% ethanol, and again filtered to give 217.7 g. of thedesired product having a decomposition point of 196°-200° C. The producthad the following analysis:

Found: C, 50.75; H, 4.33; N, 7.78; Zn, 11.02 Calc. for C₂₀ H₂₀ N₂ O₂ S₄Zn.C₅ H₅ N: C, 50.67; H, 4.22; N, 7.90; Zn, 11.05

EXAMPLE 16 Zinc Bis(2-phenyloxazolidine-3-carbodithioate) ##SPC16##

A 50.0 g. sample of the above pyridine adduct of Example No. 15 washeated at 110°-115° C. at 1 mm. Hg pressure for 17 hours to give 44.7 g.of the desired product which melted with decomposition at 133°-186° C.The infrared spectrum and the following analyses showed that the productcontained only 5% residual pyridine.

Found: C, 47.84; H, 4.21; Zn, 12.17; Calc. for product containing 5%pyridine: C, 48.29; H, 4.02; Zn, 12.10.

EXAMPLE 17 Zinc Bis[2-(p-chlorophenyl)oxazolidine-3-carbodithioate],Pyridine Adduct ##SPC17##

The above tautomeric mixture (m. 70°-73° C.) was prepared fromp-chlorobenzaldehyde and ethanolamine in the same manner as that for theortho-chloro isomer described by L. Daasch and H. Hanninen, J. Amer.Chem. Soc. 72, 3673 (1950). ##SPC18##

One hundred fourteen grams (0.62 mole) of the above mixture of2-(p-chlorophenyl)oxazolidine and Schiff Base was added to a solution of47 g. (0.62 mole) carbon disulfide in 200 ml. pyridine. After standingovernight at room temperature, the pyridine was removed by distillationat 0.5 mm. Hg pressure and pot temperature of 60° C. to leave a residueof 203 g. brown, sticky solid. The crude residue was vigorously washedwith water and then with isopropanol to give 132 g. of the desiredproduct, melting at 119°-132° C. with decomposition. It contained 6.00%nitrogen. Theoretical nitrogen content is 6.35%.

EXAMPLE 18 Zinc Bis[2-(1-ethylpentyl)oxazolidine-3-carbodithioate],Pyridine Adduct ##SPC19##

The starting material, i.e., the tautomeric mixture of oxazolidine andSchiff Base, was prepared from 2-ethylhexanal and ethanolamine inbenzene by azeotroping the water. The tautomeric mixture was distilled(boiling point 100°-102° C. at 3 mm.) before reacting it with CS₂.

To the cooled solution of 127 g. (0.74 mole) of the above2-(1-ethylpentyl)oxazlidine Schiff Base in 150 ml. pyridine was added57.0 g. (0.74 mole) carbon disulfide and then 68.0 g. (0.37 mole)anhydrous zinc acetate. After stirring at 45°-50° C. for one-half hour,the reaction mixture was stripped at 60° C. and 1 mm. to leave a residueof 225 g. of semi-solid product having the following analysis:

Found: C, 50.21; H, 7.43; N, 6.79; Zn, 10.53; Calc. for C₂₂ H₄₀ N₂ O₂ S₄Zn.C₅ H₅ N: C, 50.91; H, 7.07; N, 6.60; Zn, 10.28.

EXAMPLE 19 ZincBis(5-methyl-2-trichloromethyloxazolidine-3-carbodithioate), PyridineAdduct ##SPC20##

With stirring and cooling, 90.0 g. (1.2 moles) 1-amino-2-propanol wasadded to 250 ml. glacial acetic acid. After addition of 177.0 g. (1.20moles) of chloral, the reaction mixture was heated for 1 hour at 45°-50°C. The acetic acid was distilled off at 5 mm. to a pot temperature of45° C. The oily distillation residue of 236 g. was diluted with 300 cc.of hexane and chilled to 10° C. The precipitate was filtered off toobtain 36 g. of crude 5-methyl-2-trichloromethyloxazolidine, m.p.46°-54° C. A small sample, twice crystallized from hexane, melted at59°-62° C. and had the following analysis:

Found: C, 29.77; H, 4.00; N, 7.10; Calc. for C₅ H₈ Cl₃ NO: C, 29.34; H,3.91; N, 6.85

The infrared spectrum showed an NH band. ##SPC21##

A mixture of 237.0 g. (3.0 moles) pyridine, 38.0 g. (0.50 mole) carbndisulfide, 45.9 g. (0.25 mole) anhydrous zinc acetate and 102.3 g. (0.50mole) 5-methyl-2-trichloromethyloxazolidine was stirred for three hoursat 45° C. After standing overnight at room temperature the reactionmixture was diluted with one liter of water. The insoluble oil layer wasseparated, treated with 200 ml. hot isopropanol, and cooled to 5° C. Theprecipitate was filtered off to give 103.5 g of crude product. It wasdissolved in 450 ml. hot pyridine; at 10° C. the pyridine solution wasdiluted with 1500 ml. water and filtered to give 53.8 g. of the desiredproduct melting at 104°-133° C. with pyridine loss and decomposition. Ithad the following analysis:

Found: C, 29.29; H, 2.91; N, 6.17; Zn, 9.70; Calc. for C₁₂ H₁₄ Cl₆ N₂ O₂S₄ Zn.C₅ H₅ N: C, 29.00; H, 2.70; N, 5.97; Zn, 9.30.

EXAMPLE 20 ZincBis(5-methyl-2-trichloromethyloxazolidine-3-carbodithioate) ##SPC22##

A mixture of 412.0 g. (4.0 moles) triethylamine, 60.8 g. (0.8 mole)carbon disulfide, 73.2 g. (0.4 mole) anhydrous zinc acetate and 163.6 g.(0.8 mole) 5-methyl-2-trichloromethyloxazolidine was stirred at 40° C.for one hour. After standing overnight at room temperature, the reactionmixture was diluted with water and filtered to give 417.8 g. of thedesired crude product sintering at 89° C. and melting with decompositionat 128°-150° C. Extraction with chloroform and repeated crystallizationfrom benzene gave an analytical sample melting at 170°-176° C. withdecomposition. It had the following analysis:

Found: N, 4.30; Zn, 10.16; Calc. for C₁₂ H₁₄ Cl₆ N₂ O₂ S₄ Zn: N, 4,48;Zn, 10.47.

EXAMPLE 21 Zinc Bis(4,4-dimethyloxazolidine-3-carbodithioate) ##SPC23##

Thirty grams (1.0 mole) paraformaldehyde was added to a solution of 89.2g. (1.0 mole) 2-amino-2-methyl-1-propanol in 600 ml. isopropanol,temperature at 45°-64° C. After all the paraformaldehyde had dissolved,the mixture was cooled to 12° C.; 92 g. (0.50 mole) anhydrous zincacetate and 76 g. (1.0 mole) carbon disulfide were added. The reactionmixture was stirred six hours at 45°-50° C. Filtration at 5° C. gave152.6 g. of the desired product melting with decomposition at 209°-211°C. A benzene-crystallized sample had the following analysis:

Found: C, 34.92; H, 4.91; N, 6.62; Zn, 15.47; Calc. for C₁₂ H₂₀ N₂ O₂ S₄Zn: C, 34.50; H, 4.79; N, 6.71; Zn, 15.67.

EXAMPLE 22 Zinc Bis(5-phenyl-3-oxazolidinecarbodithioate) ##SPC24##

To 500 ml isopropanol was added 30 g. (1.0 mole) or paraformaldehyde and137 g. (1.0 mole) of 2-amino-1-phenylethanol, and the resulting mixturewas stirred and heated at 50° C. After the solids had all dissolved, thesolution was stirred an additional 30 minutes at 50° C. To the solution,cooled to 35° C., was added 68.7 g. (0.375 mole) of anhydrous zincacetate and 76.0 g. (1.0 mole) of carbon disulfide. Solids formed inseveral minutes whereby additional isopropanol (400 ml) was added tostir the mixture efficiently. After heating at 55° C. for two hours, themixture was cooled and filtered; the resulting solids were washedseveral times in a Waring Blendor with water, and air-dried overnight toobtain 184 g (95%) of the desired product melting at 220°-223° C.; itsIR spectrum was consistent with the structure.

Found: N, 4.90; Zn, 12.73; Calc. for C₂₀ H₂₀ N₂ O₂ S₄ Zn: N, 5.45; Zn,12.13.

EXAMPLE 23 ZincBis(5-phenyl-2-trichloromethyl-3-oxazolidinecarbodithioate) ##SPC25##

A mixture of equimolar amounts of chloral, glacial acetic acid, and2-amino-1-phenylethanol in benzene was refluxed using a Dean-Starkreceiver until no more water was formed. The benzene was distilled off;the distillation residue was triturated with ether and filtered. Thefiltrate was evaporated to obtain the crude5-phenyl-2-trichloromethyloxazolidine, m.p. 58°-64° C. Its structure wasconfirmed by its infrared spectrum and by elemental analysis of a samplemelting at 67°-69° C. after recrystallization from ether.

A mixture of 30.3 g (0.3 mole) triethylamine, 12.3 g. (0.1 mole) zincacetate, 55.0 g. (0.206 mole) 5-phenyl-2-trichloromethyloxazolidine and15.6 g. (0.206 mole) carbon disulfide was stirred at ambienttemperatures for 17 hours and then was heated at 50° C. for three hours.A reddish amber-colored semi-solid was obtained after the volatilematerials were distilled off at 50°/25 mm. Hg. The semi-solid wasdissolved in methanol and the resulting solution added to water withvigorous stirring. The solids were filtered, air-dried, and redissolvedin benzene. After drying the solution with magnesium sulfate, filteringthe mixture and evaporating the solvent, 37 g. (58%) of the desiredproduct (m.p. 91°-93° C.) was obtained; its infrared spectrum wasconsistent with the structure.

Found: N, 3.86; Calc. for C₂₂ H₁₈ Cl₆ N₂ O₂ S₄ Zn: N, 3.74.

EXAMPLE 24 Zinc Bis (2-hexyl-2-methyl-3-oxazolidinecarbodithioate),Pyridine Adduct

To a solution of 22.8g (0.30 mole) carbon disulfide in 142.6g (1.8moles) pyridine was added 76.0g (0.44 mole) crude2-hexyl-2-methyloxazolidine [b.p. 75°-80° C., 6 mm. Hg (prepared fromethanolamine and 2-octanone by azeotroping with benzene, distilled, andused immediately) over a period of five minutes at a temperature of15°-18°. After the solution was stirred an additional five minutes,25.7g. (0.14 mole) anhydrous zinc acetate was added and the flaskcontents were allowed to stir at ambient temperatures for 16 hours.After the volatiles were removed under reduced pressure, the resultingpale-yellow solids were treated with methylene chloride. The organiclayer was washed with 15 × 100 ml water (solids filtered off) and thenstripped of solvent under reduced pressures to give a viscous oil. Aftertriturating the oil with 600 ml low boiling (40°-60°) petroleum ether,the resulting yellow solid was extracted with ethyl ether; afterremoving the ether, 35g (39% conversion based on zinc acetate) whitesolid was obtained, m.p. 103°-6° C. A sample was recrystallized foranalysis from ethyl ether (m.p. 105°-7°).

Analysis: Found: C, 50.63; H, 6.93; N, 6.47; S, 19.10; Zn, 10.16; Calcd.for C₂₂ H₄₀ N₂ O₂ S₄ Zn. C₅ H₅ N: C, 50.90; H, 7.11; N, 6.59; S, 20.09;Zn 10.26.

EXAMPLE 25 Triethylammonium2-Trichloromethyl-3-oxazolidinecarbodithioate

A mixture of 114 g (0.60 mole) 2-trichloromethyloxazolidine, 121.2g.(1.2 moles) triethylamine and 68.4 g. (0.9 mole) carbon disulfide washeated at 50° for seven hours and then was left standing for 18 hours atroom temperature. The yellow solids were filtered, stirred withanhydrous ethyl ether, and filtered again to obtain 195.5 g (88.7%conversion) of the desired product, m.p. 107°-110° C.

Analysis: Found: C, 35.96; H, 5.69; N, 7.70; Calcd. for C₁₁ H₂₁ Cl₃ N₂OS₂ ; C, 35.92; H, 5.75; N, 7.62.

EXAMPLE 26 Cadmium Bis (2-trichloromethyl-3-oxazolidinecarbodithioate)##SPC26##

Cadmium acetate dihydrate (6.7g., 0.025 mole) was stirred into asolution of 18.4g. (0.050 mole) of triethylammonium2-trichloromethyloxazolidine-3-carbodithioate in 300 ml. of 95% ethanolat 30° C. The precipitate was filtered off at 5° C. and water-washed onthe filter. After drying in a vacuum desiccator, there was obtained 12.8g. of white crystals, melting at 223°-225° C. with decomposition. Itsinfra-red spectrum confirmed the desired structure and was essentiallythe same as that of the corresponding zinc and copper salts.

Analysis: Found: C, 19.07; H, 1.97; N, 4.65; Calcd.: C, 18.65; H, 1.55;N, 4.35.

EXAMPLE 27 Cupric Bis (2-trichloromethyloxazolidine-3-carbodithioate)##SPC27##

To a stirred suspension of 8.0g. (0.04 mole) of cupric acetatemonohydrate in 400 ml. of 95% ethanol at 80° C was added a solution of29.4g. (0.08 mole) of triethylammonium2-trichloromethyloxazolidine-3-carbodithioate in 400 ml. of 95% ethanolover a 30-min. period. After evaporating under vacuum at roomtemperature to one tenth of its original volume, 3 liters of distilledwater was added and the brown, insoluble product was filtered and washedon the filter with a little distilled water to give 19.3 g. of thedesired product melting at 186°-188° C. with decomposition. A smallsample for analysis was washed with hot chloroform. Its infra-redspectrum was in agreement with the structure of cupricbis(2-trichloromethyloxazolidine-3carbodithioate).

Analysis: Found: C, 19.72; H, 1.81; N, 4.52; Calcd.: C, 20.18; H, 1.68;N, 4.70.

EXAMPLE 28 Triethylammonium 2-Phenyl-3-oxazolidinecarbodithioate

To a solution of 574g (5.68 moles) trithylamine and 422g (2.84 moles)2-phenyloxazolidine (containing mainly the tautomer,N-benzylidene-2-hydroxyethylamine which was prepared according to theprocedure of L. Daasch et al. J.A.C.S. 72 3673 (1950)), was added 324g(4.26 moles) carbon disulfide at 19°-24° over a period of 40 minutes.Toward the latter part of the CS₂ -addition a yellow oil formed. Afterfive hours of vigorous stirring, the oil crystallized to a yellow solidwithin a short period whereby the temperature increased to 36°. Thesolids were transferred to a suitable flask to which was added 2 litersanhydrous ethyl ether, stirred vigorously and then filtered. After thetrituration was repeated twice more, a quantitative yield of white solidproduct was obtained m.p. 73°-75° C. An analytical sample was preparedby dissolving the solid product in warm (40°) isopropanol, cooling to25°, adding ethyl ether without precipitating the solid, cooling to 0°to precipitate the solid, and then filtering and drying the resultingsolid to give 282g (68% conversion) m.p. 75.5° - 77.5° c.

Analysis: Found: C, 58.9; H, 7.32; N, 8.23; S, 20.1; Calcd. for C₁₆ H₂₆N₂ OS₂ : C, 58.9; H, 8.03; N, 8.56; S, 19.6.

EXAMPLE 29 Triethylammonium 3-Oxazolidinecarbodithioate

N, N', N" - Tris (2-hydroxyethyl) hexahydro triazine (328g) was crackedat a vapor temperature of 74°-93° C and a pressure of 2-3 mm Hg to yield292g (3.73 moles) oxazolidine contaminated withN-methylene-2-hydroxyethylamine (trapped at -50°). To the amine mixture,maintained at -50°, was added 600 ml toluene with stirring and 606g (6.0moles) triethylamine. Carbon disulfide (456g, 6.0 moles) was added tothe cold (-20° to -52°) solution in one hour, during which time solidsformed. Stirring was continued an additional hour at 0° to 10° and thenthe mixture was filtered cold (N₂ atmosphere); the resulting solids weredried in a vacuum desiccator over NaOH to yield 335g (29.8% conversionbased on the triazine) white solid, m.p. 75°-85° C.

Analysis: Found: N, 11.0; S, 26.3; Calcd. for C₁₀ H₂₂ N₂ OS₂ : N, 11.2;S, 25.6.

EXAMPLE 30 Triethylammonium2-Trichloromethyl-3-thiazolidinecarbodithioate

A mixture of 356 g (1.72 moles) 2-trichloromethylthiazolidine*, 347 g(3.44 moles) triethylamine and 261g (3.44 moles) carbon disulfide wasstirred at ambient temperatures for 48 hours and then was filtered. Theyellow-colored solid was washed with a minimum of ether and then driedunder vacuum to give 152g (23% conversion) of product, m.p. 105-5.5C(melts with gas evol., solid forms) 160°-5° (dec, gas evol.)

Analysis: Found: C, 35.1; H, 5.56; N, 7.08; S, 24.8; Calcd: C₁₁ H₂₁ Cl₃N₂ S₃ : C, 34.4; H, 5.51; N, 7.30; S, 25.0.

EXAMPLE 31 Triethylammonium 3-Thiazolidinecarbodithioate

To a solution of 70g (0.79 mole) thiazolidine ** and 160g (1.58 moles)triethylamine in one liter ethyl ether was added 120g (1.58 moles)carbon disulfide at 21°-2° over a period of 30 minutes. After themixture was stirred at ambient temperatures for an additional 2.5 hours,it was filtered to give a pale yellow solid which was then washed with1.51. (5 × 300ml) ether to yield 201 g (96% conversion) of desiredproduct, m.p. 101°-3° C. (gas evol.)

Analysis: Found: C, 45.3; H, 8.16; N, 10.0; S, 36.6; Calcd. for C₁₀ H₂₂N₂ S₃ : C, 45.1; H, 8.33; N, 10.5; S, 36.1.

EXAMPLE 32 Sodium 2-Trichloromethyl-3-oxazolidine-carbodithioatePolyhydrate

A mixture of 11.4 g. (0.06 mole) 2-trichloromethyl-oxazolidine, 5.47g.(0.072 mole) carbon disulfide and 15.6g. (0.06 mole) of 15% aq. sodiumhydroxide was heated with stirring at 65°-70° for 17 hours. The reactionmixture was evaporated at 40°/mm Hg. The cooled residue was extractedwith anhydrous ethyl ether to yield an extract (which was set aside andused below) and a yellow residual solid which was extracted with dryacetone. The volatiles were removed from the acetone extract to give atacky solid which was then washed with a minimum of ether to yield 2.1gof yellow-orange product, m.p. 100°-120° (decomposition, gas).

The above etheral extract which had been set aside for 30 minutesproduced yellow solids which were filtered. These solids were treatedagain with ether to yield a residual solid (slightly impure product) andan extract. Solids which formed in the extract were filtered to yieldthe yellow-orange crystalline product, m.p. 105°-9° C. (dec., gas).

Analysis: Found: C, 18.88; H, 3.30; Cl, 28.59; N, 4.07; S, 20.26; Calcd.for C₅ H₅ Cl₃ NNaOS₂ . 21/2 H₂ O: C, 18.00; H, 3.02; Cl, 31.92; N, 4.20;S, 19.18.

In utilizing the compounds of this invention as accelerators in thevulcanization of elastomers, especially of ethylene-propylene-diene(EPDM) elastomers, generally from about 0.5 to 5 phr., preferably 1.5 to4 phr., of accelerator-compound are used, usually with from about 0.5 to3 phr. of sulfur as the vulcanization agent. (phr. means parts perhundred parts by weight of the elastomer). The accelerator compositionis milled into the elastomer along with the sulfur, and other optionalmodifying ingredients, for example, carbon black, stearic acid, zincoxide, naphthenic oil, and others known to the trade. The elastomer isthen normally cured (vulcanized) by heating to from about 300° to 450° Ffor from about 10 seconds to one hour, usually for about 10 - 40 minutesat about 300° - 350° F.

It has been observed that the compounds of the present invention notonly retard blooming in the cured elastomers but also generally showincreased accelerator activity as demonstrated by a significant increasein elastomer tensile strength and modulus when comparisons are made atequivalent concentrations of related accelerators and the same curingconditions. The results of the invention, in particular the unexpectednature of the non-blooming characteristic, is demonstrated by referenceto the following examples in which the vulcanization evaluations of arepresentative EPDM elastomer using both claimed and comparativeaccelerator compositions are carried out. The following recipe is used,where the amounts of ingredients are based on parts by weight perhundred parts of elastomer

    __________________________________________________________________________                              Parts by Weight                                     EPDM elastomer                                                                (ethylene-propylene-dicyclopentadiene terpolymer)                                                       100                                                 Naphthenic oil            50                                                  Carbon (FEF) black        100                                                 Zinc oxide                5                                                   2-Mercaptobenzothiazole   0.5                                                 Stearic acid              2                                                   Sulfur                    variable, 0.5 and 2                                 Accelerator               variable, 2 and 4                                   __________________________________________________________________________

The curing of vulcanizate is carried out at 320° F., removing samplesfor testing at 5, 10, 20, 30, 40 and 60 minutes intervals.

In Table 1, below, are listed the various representative compoundsevaluated as accelerators. Accelerators Numbers 1 through 9, 13, 16, 18through 23, 25 through 33 are embodied in this invention. Particularlypreferred accelerators are those identified as Nos. 1, 2, 3, 4, 8, 18,22 and 23. Comparative accelerators tested include zinc dithiocarbamateswhich have a structure somewhat similar to the compounds of the presentinvention, e.g., accelerator No. 10 is a commercial ultra-acceleratorfor elastomers. Other salts of dithiocarbamic acid, e.g., acceleratorsNo. 12 and No. 17, and zinc salts of other acids, e.g., accelerator No.11, are also known accelerators, two of which are commercial. Thephysical data for the observations on blooming are presented in Tables 2and 3.

The results establish that, in contrast to the accelerators of thisinvention, previously known accelerators 10-12 and 17 cause blooming.Blooming is also encountered in the use of spiro-compounds and4,4-disubstituted compounds, represented by accelerators No. 14 and No.24, respectively, and the zinc salt of the reaction product ofethanolamine, formaldehyde and carbon disulfide (disclosed in theaforementioned U.S. Pat. No. 3,674,701), represented by accelerator No.15. In addition, the spiro-compound is not very effective as anaccelerator. The compounds of this invention are shown to be not onlyeffective non-blooming accelerators but in several cases are even fasterthan the present commercial ultra accelerators; for example, compare No.1 with No. 12; No. 3, No. 8, No. 22 and No. 23 with No. 10 and No. 12.

                                      TABLE NO. 1                                 __________________________________________________________________________    Representative Accelerators Tested in EPDM Elastomer                          Example                                                                            Accelerator                                                              No.  No.                                                                      __________________________________________________________________________    2    1.     Zinc Bis(3-oxazolidinecarbodithioate)                             3    2.     Zinc Bis(2-trichloromethyl-3-oxazolidine-                                     carbodithioate)                                                   4    3.     Zinc Bis(2-trichloromethyl-3-oxazolidine-                                     carbodithioate), Pyridine Adduct                                  5    4.     Zinc Bis(2,2-dimethyloxazolidine-3-carbo-                                     dithioate)                                                        7    5.     Zinc Bis[2-(p-dimethylaminophenyl)oxazolidine-                                3-carbodithioate], Pyridine Adduct                                6    6.     Zinc Bis[2-(3-ethoxy-4-hydroxyphenyl)oxazoli-                                 dine-3-carbodithioate], Tripyridine Adduct                        8    7.     Zinc Bis(thiazolidine-3-carbodithioate)                           9    8.     Zinc Bis[(2-trichloromethyl)thiazolidine-3-                                   carbodithioate], Dipyridine Adduct                                10   9.     Zinc Bis(2,2-dimethylthiazolidine-3-carbo-                                    dithioate)                                                             10.    Zinc Bis(diethyldithiocarbamate)                                       11.    Zinc Bis(O,O-dibutyl phosphorodithioate)                               12.    Tellurium Tetrakis(diethyldithiocarbamate)                        24   13.    Zinc Bis (2-hexyl-2-methyl-3-oxazolidine-                                     carbodithioate), Pyridine Adduct                                  11   14.    Zinc Bis[spiro(cyclohexane-1,2'-oxazolidine)-                                 3-carbodithioate]                                                 12   15.    Zinc salt of the reaction product of ethanolamine,                            formaldehyde and carbon disulfide                                 13   16.    Zinc bis(2-methyl-2-phenyloxazolidine-3-                                      carbodithioate), Pyridine Adduct                                  14   17.    Zinc Bis(4-morpholinecarbodithioate)                              15   18.    Zinc Bis(2-phenyloxazolidine-3-carbodithioate),                               Pyridine Adduct                                                   16   19.    Zinc Bis(2-phenyloxazolidine-3-carbodithioate)                    17   20.    Zinc Bis[2-(p-chlorophenyl)oxazolidine-3-                                     carbodithioate], Pyridine Adduct                                  18   21.    Zinc Bis[2-(1-ethylpentyl)oxazolidine-3-                                      carbodithioate], Pyridine Adduct                                  19   22.    Zinc Bis(5-methyl-2-trichloromethyloxazolidine-                               3-carbodithioate), Pyridine Adduct                                20   23.    Zinc Bis(5-methyl-2-trichloromethyloxazolidine)-                              3-carbodithioate)                                                 21   24.    Zinc Bis(4,4-dimethyloxazolidine-3-carbodithioate)                22   25.    Zinc Bis(5-phenyl-3-oxazolidinecarbodithioate)                    23   26.    Zinc Bis(5-phenyl-2-trichloromethyl-3-                                        oxazolidine-carbodithioate)                                       25   27.    Triethylammonium 2-trichloromethyl-3-                                         oxazolidinecarbodithioate.                                        26   28.    Cadmium Bis(2-trichloromethyl-3-                                              oxazolidinecarbodithioate)                                        27   29.    Cupric Bis(2-trichloromethyl-3-                                               oxazolidinecarbodithioate)                                        28   30.    Triethylammonium 2-Phenyl-3-                                                  oxazolidinecarbodithioate                                         29   31.    Triethylammonium 3-Oxazolidine-                                               carbodithioate                                                    30   32.    Triethylammonium 2-Trichloromethyl-3-                                         thiazolidinecarbodithioate                                        31   33.    Triethylammonium 3-Thiazolidine-                                              carbodithioate                                                    __________________________________________________________________________

                                      TABLE NO. 2                                 __________________________________________________________________________                Vulcanizate (320° F).sup.(a) with 2 phr of Accelerator                 and 2 phr of Sulfur                                                           Tensile (psi)       Modulus, 200% (psi)                           Accelerator at cure time (min.) at cure time (min.)    Bloom after            No..sup.(b)                                                                       Example No.                                                                           5   10  20  40  60   5    10    20    40   1 - 2                  __________________________________________________________________________                                                           weeks                      2       1390                                                                              2100                                                                              2640                                                                              2700                                                                              2775                                                                              500   725  1080  1400  None                   2.sup.(c)                                                                         3       1300                                                                              2175                                                                              2625                                                                              2800                                                                              2825                                                                              850.sup.(d)                                                                        1300.sup.(d)                                                                        2250.sup.(d)                                                                        2775.sup.(d)                                                                        None                   3   4       1950                                                                              2310                                                                              2350                                                                              2475                                                                              2440                                                                              750  1050  1350  1470  None                   5   7       --   875                                                                              1175                                                                              1600                                                                              2050                                                                               --   400   475   800  None                   6   6        890                                                                              1250                                                                              1700                                                                              2150                                                                              2300                                                                              450   600   850  1090  None                   7   8        620                                                                              1030                                                                              1540                                                                              2450                                                                              2550                                                                              350   550   900  1600  None                   8   9       1600                                                                              2250                                                                              2600                                                                              2800                                                                              2900                                                                              675  1000  1350  1575  None                   9   10       750                                                                              1000                                                                              1400                                                                              1775                                                                              1975                                                                              400   450   725   875  None                   10  --      1325                                                                              2175                                                                              2800                                                                              2950                                                                              2750                                                                              550   850  1375  1650                                                         850.sup.(d)                                                                        1375.sup.(d)                                                                        2000.sup.(d)                                                                        2600.sup.(d)                                                                         Medium                11  --       690                                                                              1140                                                                              2000                                                                              2490                                                                              2490                                                                              300   500   900  1220   Light                 12  --       930                                                                              1650                                                                              2250                                                                              2675                                                                              2650                                                                              360   600   960  1240                                                         580.sup.(d)                                                                         975.sup.(d)                                                                        1500.sup.(d)                                                                        1950.sup.(d)                                                                         Light                 13  24       950                                                                              1610                                                                              2225                                                                              2600                                                                              2545                                                                              450   700  1000  1400  None                   14  11      Poor                                                                              Poor                                                                              1175                                                                              1225                                                                              1475                                                                              Poor Poor   850.sup.(d)                                                                         950.sup.(d)                                                                         Light                 15  12      1360                                                                              2300                                                                              2600                                                                              2750                                                                              2625                                                                              550   950  1290  1420   Light                 16  13      1250                                                                              1900                                                                              2575                                                                              2675                                                                              2650                                                                              525   800  1200  1700  None                   18  15      1650                                                                              2190                                                                              2500                                                                              2550                                                                              2690                                                                              660   950  1200  1350  None                   19  16      1150                                                                              1800                                                                              2150                                                                              2250                                                                              2350                                                                              490   800  1160  1400  None                   20  17      1270                                                                              2010                                                                              2400                                                                              2490                                                                              2460                                                                              550   865  1120  1300  None                   21  18      1210                                                                              1950                                                                              2475                                                                              2540                                                                              2725                                                                              500   760  1110  1450  None                   22  19      1840                                                                              2270                                                                              2450                                                                              2540                                                                              2610                                                                              750  1010  1225  1420  None                   23  20      2045                                                                              2420                                                                              2425                                                                              2410                                                                              2600                                                                              950  1175  1460  1660  None                   24  21      1610                                                                              2290                                                                              2450                                                                              2690                                                                              2700                                                                              650   915  1400  1680   Heavy                 25  22       750                                                                              1360                                                                              1990                                                                              2150                                                                              2250                                                                              400   660   990  1300  None                   26  23      1720                                                                              2200                                                                              2450                                                                              2450                                                                              2600                                                                              810  1070  1380  1600  None                   27  25      1110                                                                              1400                                                                              1675                                                                              2000                                                                              2100                                                                              450   700  1000  1400  None                   28  26       875                                                                              1750                                                                              2375                                                                              2475                                                                              2600                                                                              425   800  1200  1600  None                   29  27       810                                                                              1700                                                                              2220                                                                              2360                                                                              2570                                                                              400   750  1140  1525  None                   30  28      1350                                                                              1975                                                                              2375                                                                              2250                                                                              2400                                                                              625   900  1175  1225  None                   31  29      1200                                                                              1650                                                                              1875                                                                              2150                                                                              2225                                                                              600   800   825  1050  None                   32  30       925                                                                              1275                                                                              1475                                                                              1925                                                                              1825                                                                              425   625   825   975  None                   33  31       700                                                                              1100                                                                              1550                                                                              1875                                                                              2150                                                                              400   500   785   850  None                   __________________________________________________________________________     .sup.(a) except where marked with (c);                                        .sup.(b) see Table No. 1 for names of accelerators;                           .sup.(c) cure temperature was 305° F instead of 320° F;         .sup.(d) 300% modulus                                                    

                                      TABLE NO. 3                                 __________________________________________________________________________                Vulcanizate (320° F).sup.(a) with 4 phr of Accelerator                 and 0.5 phr of Sulfur                                                         Tensile (psi)       Modulus, 200% (psi)                           Accelerator at cure time (min.) at cure time (min.)    Bloom after            No..sup.(b)                                                                       Example No.                                                                           5   10  20  40  60   5    10    20    40   1 - 2                  __________________________________________________________________________                                                           weeks                  1   2        780                                                                              1290                                                                              1900                                                                              2000                                                                              1980                                                                              300   430   690   750  None                   2.sup.(c)                                                                         3        800                                                                              1375                                                                              1975                                                                              2400                                                                              2450                                                                              575.sup.(d)                                                                         850.sup.(d)                                                                        1400.sup.(d)                                                                        1650.sup.(d)                                                                        None                   4   5       1010                                                                              1875                                                                              2080                                                                              2250                                                                              2120                                                                              500   750   950   960  None                   6   6        600                                                                               820                                                                               910                                                                               890                                                                               890                                                                              300   350   450   400  None                   7   8       --   700                                                                              1060                                                                              1460                                                                              1510                                                                               --   350   500   700  None                   8   9       1000                                                                              1550                                                                              2010                                                                              1950                                                                              1870                                                                              400   650   850   860                                                         660.sup.(d)                                                                        1010.sup.(d)                                                                        1300.sup.(d)                                                                        1310.sup.                                                                           None                   10  --      1200                                                                              1980                                                                              2300                                                                              2375                                                                              2210                                                                              480   775   990  1000                                                         780.sup.(d)                                                                        1240.sup.(d)                                                                        1509.sup.(d)                                                                        1550.sup.(d)                                                                         Heavy                 11  --       790                                                                              1025                                                                              1510                                                                              1890                                                                              1775                                                                              350   440   600   750   Light                 12  --       770                                                                              1450                                                                              1820                                                                              1850                                                                              1800                                                                              310   610   690   760   Medium                13  24       850                                                                              1300                                                                              1810                                                                              1930                                                                              1950                                                                              390   560   750   850  None                   14  11      Poor                                                                              Poor                                                                              Poor                                                                               475                                                                               500                                                                              Poor Poor  Poor   350   Light                 15  12       775                                                                              1250                                                                              1550                                                                              1450                                                                              1570                                                                              380   600   650   650   Light                 16  13      1230                                                                              1700                                                                              2000                                                                              1925                                                                              2050                                                                              500   690   850   875  None                   17  14      Poor                                                                              Poor                                                                               630                                                                               940                                                                              1050                                                                              Poor Poor   250   400   Light                 18  15      1250                                                                              1650                                                                              1710                                                                              1630                                                                              1690                                                                              550   725   725   725  None-Trace             20  17      1250                                                                              1620                                                                              1700                                                                              1590                                                                              1580                                                                              600   660   710   700  None                   21  18      1100                                                                              1600                                                                              1860                                                                              1830                                                                              1900                                                                              500   650   780   760  None                   22  19      1460                                                                              1900                                                                              2050                                                                              2000                                                                              1890                                                                              570   800   900   900  None                   23  20      1310                                                                              1840                                                                              2100                                                                              2040                                                                              2240                                                                              550   790  1000  1040  None                   24  21      1160                                                                              1825                                                                              2050                                                                              2190                                                                              2125                                                                              500   800   950   950   Heavy                 26  23      1300                                                                              1700                                                                              1800                                                                              1675                                                                              1675                                                                              590   800   840   850  None                   27  25      1025                                                                              1100                                                                              1200                                                                              1200                                                                              1200                                                                              425   450   500   575  None                   28  26      --  --  1500                                                                              1900                                                                              1900                                                                               --   --    625   800  None                   29  27      --   750                                                                              1025                                                                              1410                                                                              1410                                                                               --   --    475   700  None                   __________________________________________________________________________     .sup.(a) except where marked with (c);                                        .sup.(b) see Table No. 1 for names of accelerators;                           .sup.c cure temperature was 305° F instead of 320° F;           .sup.(d) 300% modulus.                                                   

We claim:
 1. In the method of curing ethylene-propylene-diene elastomerswherein the elastomer composition, having admixed therein sulfur, avulcanization accelerator and other rubber compounding ingredients, iscured at elevated temperature, the improvement which comprises using asthe accelerator a compound of the structure ##SPC28##where X is sulfuror oxygen, R, R¹, R² and R³ are independently selected from the groupconsisting of hydrogen, lower alkyl having from 1 to 8 carbon atoms,CCl₃, phenyl and substituted phenyl wherein there are not more than twosubstituents on any one phenyl group, said substituents selected fromthe group consisting of NR⁴ R⁵, OR⁶ and Cl where R⁴ and R⁵ areindependently selected from the group consisting of hydrogen and methyl,R⁶ is selected from the group consisting of hydrogen and lower alkylhaving from 1 to 8 carbon atoms, not more than one of R and R' is phenylor substituted phenyl and not more than one of R² and R³ is phenyl orsubstituted phenyl; C₅ H₅ N represents a pyridine molecule and n is aninteger of zero to 5; M is selected from the group consisting of Na, K,Zn, Cd, Cu, Fe, Tri (C₁ -C₈) alkyl substituted ammonium and phenyl di(C₁ -C₈) alkyl substituted ammonium; and y is an integer of 1 to 3corresponding to the valency of M.
 2. A method according to claim 1wherein X is sulfur.
 3. A method according to claim 1 wherein X isoxygen.
 4. A method according to claim 1 wherein R, R¹, R² and R³ areeach hydrogen, X is oxygen, M is Zn and y is
 2. 5. A method according toclaim 1 wherein R is hydrogen, R¹ is CCl₃, R² and R³ are each hydrogen,X is oxygen, M is Zn and y is
 2. 6. A method according to claim 5wherein n is zero.
 7. A method according to claim 5 wherein n is
 1. 8. Amethod according to claim 1 wherein R, R¹, R² and R³ are each hydrogen,X is oxygen, M is (C₂ H₅)₃ NH, y is 1 and n is zero.
 9. A methodaccording to claim 1 wherein R and R¹ are each methyl, R² and R³ areeach hydrogen, X is oxygen, M is Zn, y is 2 and n is zero.
 10. A methodaccording to claim 1 wherein R is hydrogen, R¹ is CCl₃, R² and R³ areeach hydrogen, X is sulfur, M is Zn, and y is
 2. 11. A method accordingto claim 10 wherein n is
 2. 12. A method according to claim 1 wherein Ris hydrogen, R¹ is CCl₃, R² is hydrogen, R³ is methyl, X is oxygen, M isZn, y is 2 and n is zero.
 13. A methhod according to claim 1 wherein R,R¹, R² and R³ are each hydrogen, X is sulfur, M is (C₂ H₅)₃ NH, y is 1,and n is zero.